GWEN IFILL: Finally tonight, the latest on efforts to ramp up air safety through a new technology. At a homeland security hearing today, Secretary Janet Napolitano told senators she believes new screening techniques are a key part of a larger strategy to stop terrorism.
JANET NAPOLITANO: Once you have identified a problem, you have got to fix it. But we also need to be thinking ahead to be proactive. That's why, for example, we have entered into this agreement to really get some of the best scientists in the world who are in our national labs thinking well ahead about the next generation of screening technology and what it can show us.
GWEN IFILL: Ray Suarez has been looking into some of the latest technology being rolled out in the nation's airports.
Here's his report.
RAY SUAREZ: It's been almost a month since Umar Farouk Abdulmutallab allegedly tried to blow up Northwest Flight 253. Since then, the debate over how to keep the flying public safe has intensified, and a chief focus has been the use of so-called body scanners.
Top security officials have sped up deployment of the scanners. Currently, there are only 40 machines in 19 of the 450 commercial airports in the United States that follow TSA security procedures. Four hundred and fifty more of the machines will come online this year to screen passengers for items concealed under layers of clothing. Three hundred and fifty of those will be paid for with recently allocated money. The machines cost more than $150,000 a piece.
But there are those with concerns about the flying public's privacy and health. There are two kinds of machines. The first, millimeter wave, is a booth that uses harmless electromagnetic waves to create a three-dimensional image. The other kind, a backscatter machine, takes a double X-ray to create a two-sided image.
Dr. Mahadevappa Mahesh, chief physicist at Johns Hopkins University Hospital, showed us how they work. He said the radiation levels, especially with the backscatter machine, are not high.
DR. MAHADEVAPPA MAHESH, chief physicist, Johns Hopkins University Hospital: The radiation dose levels are quite low. When I say quite low, let's give a comparison with respiratory medical chest X-ray, let's say. Compared to a medical chest X-ray, typical backscatters you need to acquire or go through these scanners nearly 1,000 to 2,000 times before the dose reaches to a typical chest X-ray.
RAY SUAREZ: All in all, Mahesh believes the body scanners are safe, but that people in high-risk groups like pregnant women and children should have the option not to use them.
DR. MAHADEVAPPA MAHESH: What I have known recently is like we have a couple of airports in the U.S. which have installed both of these technologies. And, right now, they are giving public the option to go through these things and they have an option to not go through these things.
RAY SUAREZ: Even if the Federal Aviation Administration is able to convince travelers the machines are safe, there is still the privacy concern. The American Civil Liberties Union has called the use of scanners a virtual strip-search.
Mark Rotenberg, executive director of the Electronic Privacy Information Center in Washington, says privacy is being compromised for a machine that doesn't even detect all harmful materials.
MARK ROTENBERG: If you look at the design specifications, you see references to explosives and to weapons and to liquids, but not to powders. And that's significant, because PETN is a powdered explosive. It's what Abdulmutallab used on December 25. It's what the shoe bomber, Richard Reid, tried to use previously. It's very difficult to detect. It's not obvious that these devices would have found it.
RAY SUAREZ: But Mahesh argues, the steps taken to ensure privacy, like blurring faces, render people anonymous.
DR. MAHADEVAPPA MAHESH: What happens is, like, the person who is asking the public to scan is not there next to the scanner. He's somewhere remotely. So, there's less chances of somebody seeing a supermodel next to the scanner, and next see their image and trying to sell it off to "The National Enquirer" and all those things that has been the concern of the public.
RAY SUAREZ: For Rotenberg, that is just not good enough.
MARK ROTENBERG: I think the TSA has actually been very misleading on this point. In fact, they're going to detect prosthetics. They're going to detect mastectomy scars. They're going to detect sex change operations, adult incontinence. Those are the types of images that will be available to the TSA operators.
RAY SUAREZ: At Baltimore Washington International Airport recently, many of the passengers we spoke with seemed comfortable being scanned.
GARY BREITBORD: No particular concerns. As long as they don't damage me, right, they're not harmful health-wise, then that's fine.
LAURIE ADAMS: If that was -- the technology is there that they're looking for bombs or unsecured -- or secured instruments that people can hurt myself or any other passenger, then deal with it or drive.
RAY SUAREZ: But at Chicago's O'Hare Airport, just days after the foiled Christmas bombing, some said the government should be doing more to uncover terror plots, instead of bothering innocent people.
DEBBIE BORMAN: I feel like they're not doing -- the governments are not doing a really great job at the front end, finding people who really are trying to do something to other people, whereas, like, all the rest of us are just going to visit friends, going to visit family. We're not doing anything. And it's so invasive, possibly to the point of unconstitutional.
RAY SUAREZ: Former Homeland Security Chief Michael Chertoff, who is a consultant for one company that manufactures body scanners, says that, given the capability and intent of terrorists, we may have to trade some privacy for security.
MICHAEL CHERTOFF: So, now you have to ask yourself this question. Once we have the privacy protections in place, are you prepared to accept a certain amount of discomfort in someone looking at what may you have concealed on your body, in return for knowing that you're not going to have a plane detonate in midair?
And I think I know, speaking for myself, and, you know, I imagine most people, most people I have spoken to would rather make sure they get to their destination safely, even if it means adjusting their privacy expectations.
RAY SUAREZ: When all is said and done, could body scanning machines have prevented the Christmas Day attack? Chertoff thinks so.
MICHAEL CHERTOFF: Are they perfect? No. But do they take us very much further down the road to security against this kind of device? The answer to that is yes.
RAY SUAREZ: During the last debate over body imaging, the opponents won the argument. After the Christmas Day bomb attempt, even if controversies continue, Americans can expect to see more body scanners when they fly.